Tried to modify Michigan due to its huge popups but could not get it to work (I tried it with all of the program versions here).
I can change the values and write them (i.e. the program as such appears to work) but when I go to GPL and click the green button to load the track then it sort of freezes.
I tried to modify Watkins Glen (= any standard track) and it appeared to work.

Hint: I made a test. I opened the .trk and then the michigan.3do and then did NOT change any value but just wrote the .3do and that was enough to make GPL stop loading the track.
So is there something (a limitation?) about these converted tracks (e.g. Michigan)?
any help appreciated.

You could try to open the track.3do with racecon.
Change a name somewhere and change it back then save.
If the track then still works you could have a go with the tool.
Racecon restructures the 3do and sometimes repairs flaws in the 3do.

Errors in 3do's sometimes cause no problem in GPL but resaving them in the editor or other tools might make the 3do defunct.
Most of the time it's caused by faulty length values in the 3do sections.

You could try to open the track.3do with racecon.
Change a name somewhere and change it back then save.
If the track then still works you could have a go with the tool.
Racecon restructures the 3do and sometimes repairs flaws in the 3do.

Errors in 3do's sometimes cause no problem in GPL but resaving them in the editor or other tools might make the 3do defunct.
Most of the time it's caused by faulty length values in the 3do sections.

Hi MECH
Is it possible to find out why JANAKKALA does not work with RaceCon ?
Cheers ... XK